1. Field of the Invention
This invention relates to a thermoelectric module having a large number of thermoelectric elements arranged thereon.
2. Description of the Related Art
As shown in FIG. 7, a conventional thermoelectric module 1 has been produced by cutting out prism thermoelectric elements 3 from an ingot of a thermoelectric material prepared by melt growth such as zone melting, bonding the thermoelectric elements 3 to upper and lower electrodes 4 made of an electrically conductive material by soldering and the like to provide a predetermined conducting pattern, and fixing a heat exchanger plate 5 on each outer side of electrodes 4. When the thermoelectric element 3 and the electrode 4 are bonded with solder, there is formed a solder fillet 7 around the joint as shown in FIG. 8. The thermoelectric module 1 thus completed has a neat structure and enjoys the advantage that the thermoelectric elements 3 exhibit constant heat and constant heat conduction. Having a flat surface on each side, the thermoelectric module 1 is suited to production of a panel type apparatus having a thermoelectric element bonded to each side thereof.
However, because the thermoelectric elements 3 (i.e., p-type thermoelectric elements 3a and n-type thermoelectric elements 3b) are made of brittle materials, they tend to develop cracks or breaks in case a shock or a load is imposed to the thermoelectric module 1 or in case a thermal stress is applied to the thermoelectric element 3. In addition, because the thermoelectric elements 3 have poor moisture resistance, they tend to undergo corrosion in a high humidity atmosphere, resulting in deterioration of performance.